Marine propulsion device with improved exhaust discharge

Abstract

A marine propulsion device (1) includes a drive housing (6) to which is attached a suitable engine (4), the exhaust of which is pumped downwardly through a suitable passage (20) in the drive housing to adjacent a torpedo housing (7) carrying at least one propeller (9,10). A generally horizontal antiventilation plate (8) is disposed above the torpedo housing, and a strut (22) extends between the plate and the torpedo housing, just forwardly of the upper portion of the propeller. Substantially all of the engine exhaust is forced by the engine from the drive housing passage for discharge into the path of the upper portion of the propeller. In one embodiment, substantially all of the exhaust passes through the strut and is discharged rearwardly therefrom into ventilating engagement with the forward face of the propeller. In another embodiment, a portion of the exhaust (31) is also discharged downwardly through the antiventilation plate onto the upper edge portion of the propeller.

I claim: 
     
       1. In a marine propulsion device, the combination comprising: (a) a generally vertically extending drive housing (6) connected to a marine engine (4) and adapted to extend downwardly into the water,   (b) a generally horizontal fore-to-aft extending torpedo housing (7) disposed at the lower end portion of said drive housing,   (c) propeller means designed for surface running and being mounted aft of said torpedo housing and drivingly connected through the latter and said drive housing to said engine,   (d) a substantially closed-walled generally vertical engine exhaust passage (20) disposed in said drive housing and connected to said engine, said exhaust passage having a discharge portion at the lower passage end,   (e) and essentially total exhaust discharge means (21,22) communicating with said exhaust passage discharge portion and disposed forwardly of said propeller means for discharging substantially all of the engine exhaust into the path of said propeller means to enhance performance of the latter.   
     
     
       2. The combination of claim 1 in which said essentially total exhaust discharge means discharges substantially all of said engine exhaust generally horizontally rearwardly toward said propeller means. 
     
     
       3. The combination of claim 1 in which said essentially total exhaust discharge means: (a) discharges a first exhaust portion (28) horizontally rearwardly toward said propeller means,   (b) and discharges a second exhaust portion (31) generally downwardly onto said propeller means.   
     
     
       4. The combination of claim 1 in which said essentially total exhaust discharge means discharges a portion (31) of said exhaust downwardly onto said propeller means. 
     
     
       5. The combination of claim 1: (a) which includes a generally horizontal antiventilation plate (8) disposed on said drive housing (6) above said torpedo housing (7),   (b) and in which said essentially total exhaust discharge means comprises: (1) a strut (22) disposed between said antiventilation plate and said torpedo housing,   (2) said strut having a chamber (23) communicating with said exhaust passage (20),   (3) and a discharge opening (24) in said strut for discharging engine exhaust from said chamber toward said propeller means.     
     
     
       6. The combination of claim 5: (a) which includes an opening (21) in said antiventilation plate (8), and with said last-named opening communicating between said exhaust passage discharge portion and said strut chamber (23),   (b) and the rearward portion (26) of said last-named opening (21) terminates above the forward portion of said propeller means,   (c) the construction being such that said discharge opening (24) discharges substantially all of said engine exhaust horizontally rearwardly toward said propeller means.   
     
     
       7. The combination of claim 5: (a) which includes an opening (21) in said antiventilation plate (8), and with said last-named opening communicating between said exhaust passage discharge portion and said strut chamber (23),   (b) and the rearward portion (31) of said last-named opening (21) terminates above the blade tip portions (29) formed by said propeller means,   (c) the construction being such that: (1) a first exhaust portion (28) is discharged from said discharge opening (24) and horizontally rearwardly toward said propeller means,   (2) and a second exhaust portion (31) is discharged through said antiventilation plate and generally downwardly onto said blade tip portions (29).     
     
     
       8. The combination of claim 1, 2, 3, 4, 5, 6 or 7 in which: (a) said propeller means comprises a pair of coaxially mounted forward (10) and rearward (9) contra-rotating surfacing propellers,   (b) the construction being such that said essentially total exhaust discharge means (21,22) causes exhaust to impinge on the entire forward portion of said forward propeller, and with a portion of the exhaust being forced rearwardly between the blades of said forward propeller for impingement on the forward portion of said rearward propeller.